Astro.Earth (Astro v0.8.0) View Source

Constants and astronomical calculations related to the earth.

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Functions

Adjusts the solar elevation to be the apparent angle at sunrise if the requested angle is :geometric (or 90°)

Returns the radius of the earth in kilometers

Adjusts the solar elevation to account for the elevation of the requested location

Returns the obliquity of the earth

Returns an estimate of the effect of refraction applied to the calculation of sunrise and sunset times.

Returns the suns apparent radius at sunrise/sunset.

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adjusted_solar_elevation(solar_elevation, elevation)

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Adjusts the solar elevation to be the apparent angle at sunrise if the requested angle is :geometric (or 90°)

Arguments

  • solar_elevation is the requested solar elevation in degress. It will be 90° for sunrise and sunset.

  • elevation is elevation in meters

Returns

  • The solar elevation angle adjusted for refraction, elevation and solar radius.

Returns the radius of the earth in kilometers

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elevation_adjustment(elevation)

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Adjusts the solar elevation to account for the elevation of the requested location

Arguments

  • elevation is elevation in meters

Returns

  • The solar elevation angle adjusted for the elevation
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nutation(julian_centuries)

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Specs

Returns the obliquity of the earth

Returns an estimate of the effect of refraction applied to the calculation of sunrise and sunset times.

Sunrise actually occurs before the sun truly reaches the horizon because earth's atmosphere refracts the Sun's image. At the horizon, the average amount of refraction is 34 arcminutes, though this amount varies based on atmospheric conditions.

This effect is especially powerful for objects that appear close to the horizon, such as the rising or setting sun, because the light rays enter the earth's atmosphere at a particularly shallow angle. Because of refraction, the sun may be seen for several minutes before it actually rises in the morning and after it sets in the evening.

Returns the suns apparent radius at sunrise/sunset.

Unlike most other solar measurements, sunrise occurs when the Sun's upper limb, rather than its center, appears to cross the horizon. The apparent radius of the Sun at the horizon is 16 arcminutes.